This invention relates to a field marker for attachment to an agricultural implement for generating a mark in the field at a position spaced outwardly to one side of the implement, wherein the marker includes a self supporting arrangement reducing the amount of weight applied to the implement during operation.
Markers for agricultural implements are used to allow the operator to more accurately drive the implement in a required direction as required spacing from a previous swath of the implement to avoid double coverage or missed spaces.
The most simple form of marker simply includes a disc or other element which scores a mark across the ground and is mounted on an arm which projects outwardly to one side of the implement to a distance approximating one half of the width of the implement.
As implements have become wider, the length of the arm has necessarily become longer thus increasing the amount of strength and weight necessary for the arm to ensure that the disc marker remains properly in position forming the required furrow. As the implement has also become wider, it will be necessary to provide a more complex folding action allowing the implement to a folded position for transport. Many seeders therefore have a double wing arrangement so that each wing section is formed of an inner portion and an outer portion so that as the inner section is folded to a vertical orientation the outer section is folded to a horizontal orientation upside down or even beyond the horizontal to a position depending downwardly toward the centre section.
In order to provide the necessary length of arm and in order to provide the mounting of the arm accommodating the folding action, folding markers have been developed which lie alongside the end beam of the implement in a retracted position and fold outwardly in two portions so as to extend the required length to the marker disc.
Examples of these designs of marker are shown in U.S. Pat. No. 4,512,416 (Smith), U.S. Pat. No. 5,425,427 (Haugen); U.S. Pat. No. 5,027,525 (Haukaas) and U.S. Pat. No. 5,785,128 (Redekop).
An additional problem for markers of this type is that the increased length and weight which has become necessary requires that the weight is to some extent transferred to the implement. All of the markers transfer some weight to the implement and particularly in the retracted position, all of the markers are supported on the implement and therefore their whole weight is carried on the implement. While the effect of the weight is reduced in the extended position, in some designs of seeder even this weight in the extended position is unacceptable since the weight tends to tilt the outer wing section thus interfering with the proper levelling action of the implement connections and thus interfering with the proper seeding depth. More specifically, the weight on the outside edge of the wing section of the implement causes the seeding elements adjacent that edge to seed to deeply while the seeder elements at the opposite edge of the wing section are raised and thus seed too shallowly.
For this reason implements manufactured by certain manufacturers have been unable to accommodate markers of this general type and up till now no marker has been available which could be used effectively while allowing the seeding depth to be properly maintained.
It is one object of the present invention, therefore, to provide an improved field marker which is at least partly self supporting during operation.
According to one aspect of the invention there is provided a field marker comprising:
a mounting member arranged for mounting on an agricultural implement at one side thereof;
a marker arm attached to the mounting member for movement between a deployed position extending outwardly of the implement to one side thereof and a retracted position;
a marker element carried on a free end of the marker arm for engaging the ground, when the arm is in the deployed position, and forming a mark on the ground parallel to movement of the implement across the ground;
the marker arm including an inner arm portion having an inner end attached to the mounting member and an outer arm portion attached to an outer end of the inner arm portion with the marker element on an outer end of the outer arm portion;
the inner arm portion being mounted on the mounting member for pivotal movement about a horizontal axis to allow the marker arm to move upwardly and downwardly relative to the implement;
a ground support wheel mounted on the inner arm portion so as to support the outer end of the inner arm portion relative to the ground;
the outer arm portion being mounted on the outer end of the inner arm portion for pivotal movement about a horizontal axis to allow the marker element to move upwardly and downwardly relative to the implement;
a deployment member for effecting pivotal movement of the marker arm about a generally upright axis from the deployed position to a retracted position approximately 90xc2x0 to the deployed position in which the marker arm trails rearwardly of the mounting member;
the deployment member and the ground wheel being arranged relative to the marker arm such that the marker arm is supported by the ground wheel and is free to pivot relative to the mounting member about the horizontal axis in the deployed position, the retracted position and as it moves from the deployed position to the retracted position.
Preferably the ground wheel is a castor wheel.
Preferably the outer arm portion is pivotally mounted on the inner arm portion for movement from a deployed position extending outwardly of the inner arm portion to a retracted position folded alongside the outer arm portion.
Preferably the outer arm portion pivots about a substantially horizontal axis so as to move upwardly onto a top of the inner arm portion.
Preferably each of the outer arm portion and the inner arm portion comprises two parallel bars lying in a substantially horizontal plane.
Preferably the marker arm and the ground wheel are arranged such that the marker arm extends rearwardly over a top of the implement frame in the retracted position.
Preferably the marker arm and the mounting member are positioned within an outermost end member of the frame of the implement in a retracted position so as to avoid any projection beyond the outer most frame member.
Preferably there is provided an abutment post attached to the implement frame and standing upwardly therefrom at a position rearwardly of the mounting member for abutting the marker arm in the retracted position while allowing the marker arm to pivot upwardly and downwardly.
Preferably the latch post includes a latch member movable to a latch position to engage the marker arm as the implement is folded upwardly to a folded position of the implement.
Preferably each of the inner and outer marker arm portions includes two bars arranged in common plane with one in advance of the other and wherein the marker element comprises a disc for rolling on the ground and wherein one bar of the outer portion extends outwardly to a position adjacent or just beyond the disc in advance of the disc to act as a guard bar for impacting any obstacle in advance of the disc.
Preferably the mounting member includes a compression spring pushing down on the marker arm so as to transfer weight from the mounting member outwardly to the ground wheel.
Preferably the outer portion pivots upwardly and inwardly to a retracted position on top of the inner portion and wherein there is provided a lift cylinder for actuating movement of the outer portion while allowing pivotal movement of the outer portion relative to the inner portion when in the deployed position, the actuating cylinder including a lever pivotally mounted on the outer portion and including an abutment outwardly of the pivot for engaging the outer portion.
Preferably the lever includes a spring biasing the cylinder and lever into an overcenter position.
Preferably there is provided a cylinder for moving the arm from the deployed position to the retracted position and vice versa, a free end of the cylinder being mounted on a trip mechanism such that the marker arm can move to the retracted position if tripped by impact with an obstacle and such that when in the retracted position following a trip, the cylinder can be returned to the untripped position by actuating the cylinder to move the marker arm to the retracted position.